The most likely fix on a Jandy AquaPure showing Check Cell: verify actual salinity at a lab before doing anything else. Most Check Cell calls in South Florida are pools that drifted under 2,800 ppm after rain or backwash. Add salt, run a diagnostic. If salt is correct, water is warm, and Check Cell persists, work the path: cell scale, then flow switch, then board. Cell replacement is the last assumption, not the first.
Jandy AquaPure symptom quick reference
| Code / symptom | What it means | Likely cause | DIY or pro? |
|---|---|---|---|
| Check Cell lit | Controller flagging the cell or salt reading | Salt drifted under 2,800 ppm after rain or backwash, cell scale, or an aging cell | DIY first, then pro |
| No Flow with the pump clearly running | Flow switch not closing | Paddle stiffened with age and lime, or grit in the switch | Pro |
| Powers up but produces no chlorine | Unit not generating | Low salt or cold water near the 50°F cutoff | DIY first, then pro |
| Display dim, flickering, or dark with line voltage present | Controller board problem | Humidity or lightning damage — scorched relays, swollen capacitors | Pro |
| White crust on the cell plates | Hard-water scale | High-calcium fill water; common in Boca, Delray, and Coral Springs | DIY first, then pro |
Most common symptoms
- Check Cell lit on the controller despite normal salt readings.
- No Flow warning when the pump is clearly running.
- AquaPure powers up but produces no chlorine.
- Display dim, flickering, or completely dark with line voltage at the unit.
- Cell makes a buzzing or chattering sound when generating.
Diagnostic walkthrough
- Salt at the lab first. The AquaPure's onboard salt reading drifts as the cell ages. A handheld photometer or pool-store reading is the truth. Confirm your model's target range against the Jandy AquaPure manual — current models target a 3,000–4,500 ppm range with a 3,200 ppm sweet spot. Add salt to range first; many Check Cell complaints clear with that alone.
- Water temperature. Most AquaPure controllers stop generating once water drops near 50°F — verify the cold-water cutoff for your specific model in the Jandy manual. Florida pools see this on January cold snaps, especially if the heater is off. Wait for 60°F+ before assuming a fault.
- Inspect the cell. Pull it. Hard scale on the plates looks like white crust. Acid-wash with a 4:1 dilution (four parts water to one part muriatic acid), plates submerged ~10–15 minutes. Always pour acid into water, never water into acid; wear chemical splash goggles, gloves, and long sleeves; work outdoors; and never mix the bath with chlorine products (chlorine gas). Reinstall and run a diagnostic.
- Test the flow switch. The paddle stiffens with age and lime. Pull the switch, work the paddle by hand, look for grit. Jumper the two flow-switch leads at the controller — if the unit now thinks there is flow, you confirmed the switch.
- Open the controller. With power off. Look for visible board damage: scorched relays, swollen capacitors, dead-bug spots. Florida humidity kills these boards faster than the cells.
Step-by-step fix
For low salt: add salt, wait two pump cycles, retest. For scale: acid-wash and reinstall. For a sticky flow switch: clean or replace the paddle assembly — cheap part, common failure. For a board: replace the AquaPure controller; do not attempt component-level repair on a 240V outdoor PCB.
South Florida-specific failure modes
- Hard water scale. Boca, Delray, Coral Springs — high calcium fill. Quarterly cell inspection is realistic, not optional.
- Lightning damage to the PCB. AquaPure controllers near a strike take out the surge-suppression first, then the relays. Whole-pad surge protection helps; a direct hit still wins.
- Salt cell corrosion at the cable terminal. Coastal pools see green oxide build at the cell-to-cable junction within 5 years. Dielectric grease at install slows this.
- Calcium chip-out on aged cells. Repeated acid-washing on a 5-year cell starts pulling the plate coating with the scale. There is a point where you stop washing and start replacing.
When it's time to replace
Cell with 9,000+ hours, multiple acid-washes, and still failing the diagnostic — replace the cell. Controller with a visibly damaged board, intermittent display, or relay chatter — replace the controller. If both are 6+ years old, replace as a system; the labor is the same and you avoid a return visit. See our salt chlorine generators primer for system-level context.
When to call a pro
Anything past salt, temperature, and a basic acid-wash is pro territory. The AquaPure controller carries 240 V on the input side — lock out the breaker before opening it, and consider that pro work either way. The flow switch is a 30-second swap when you know what you are doing and a half-hour fight when you don't. In Florida, residential pool repair work is regulated by the DBPR (RP / CPC license categories). Schedule a pool equipment repair visit for diagnosis and a flat-rate quote.
Pool salt calculator
Enter your pool size, current salt reading, and your cell's target. Math: (target − current) × gallons ÷ 120,000 = lbs of salt.
From a salt test strip or your cell's display.
Add ≈ 90 lbs of pool salt
That's 3 × 40-lb bags (exact math: 87.5 lbs to go from 2,500 to 3,200 ppm in 15,000 gallons). Broadcast it into the pool — never the skimmer — run the pump 24 hours, then retest.
Use 99.8%+ pure sodium chloride pool salt only — never water-softener, rock, or iodized salt.
Frequently asked questions
Check Cell is the AquaPure flagging that something between the controller and the cell is wrong. It is not necessarily the cell itself. Three causes: low salinity (most common), low water temperature below the cell's operating threshold, or genuine cell wear. Verify salt at a lab before replacing anything.
Pull the flow-switch assembly. Inspect the paddle for stiffness or debris. With pump off and switch out, jumper the two flow-switch wires together at the PCB — if the AquaPure now believes there is flow and tries to generate, the paddle is the problem.
Jandy rates the AquaPure cell at roughly 10,000 hours of generation, which works out to 4–6 years on a typical Florida pool. Cells used in pools running aggressive output 24/7 during the heat months wear faster.
When the cell tests good (correct voltage when bench-tested), the salinity is correct, the flow switch is good, and the unit still won't generate or refuses to power up — the PCB is the suspect. Look for visible burn marks, swollen capacitors, or relays that won't latch.
Yes. 4:1 water-to-muriatic-acid soak, plates fully submerged, 10–15 minutes. Rinse and reinstall. Florida hard water and high LSI scale these cells fast — clean every quarter on calcium-prone pools.
The flow switch isn't closing. The paddle stiffens with age and lime, or grit gets into the switch body. Pull it, work the paddle by hand, and look for debris. Jumper the two flow-switch leads at the controller — if the AquaPure suddenly believes there is flow, you've confirmed the switch. It's a cheap part and a common failure, but it sits on a 240V unit, so treat it as pro work.
Most AquaPure controllers stop generating once water drops near 50°F — a built-in cold-water cutoff, not a fault. South Florida pools hit this on January cold snaps, especially with the heater off. Verify your model's cutoff in the Jandy manual and wait for water above 60°F before assuming something is broken.
Yes — it's one of the most common South Florida failure modes. A nearby strike takes out the surge suppression first, then the relays. Look for scorched relays, swollen capacitors, or a dim, flickering display with line voltage present. Whole-pad surge protection helps, but a direct hit still wins. A damaged board means replacing the controller, not component-level repair.
If both are 6+ years old, yes — replace as a system. The labor is the same visit either way, and you avoid a return trip when the second aging component fails a few months later. A cell at 9,000+ hours and a controller with an intermittent display or relay chatter are each near end-of-life on their own.
When repeated washes start doing damage. On a 5-year-old cell, acid-washing begins pulling the plate coating off with the scale. A cell with 9,000+ hours of generation, multiple acid-washes behind it, and a failed diagnostic is done — replace it instead of washing it again.
AquaPure still throwing codes?
We diagnose and repair Jandy salt systems across Palm Beach and Broward — flat-rate quote in writing before any work.